<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html lang="en">
<head>
    <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
    <title>Document</title>
    <style type="text/css">
        div {
            width: 100%;
            height: 1000px;
            background-color: bisque;
            display: flex;

            /*换行*/
            flex-wrap: wrap;
            /*设置换行的子元素，上下对其*/
            /*align-content: space-between;*/

            /*平分剩余空间*/
            align-content: space-around;

        }
        span {
            width: 300px;
            height: 300px;
            background-color: aqua;
            margin: 10px;
        }
    </style>
</head>
<body>
<div>
    <span>1</span>
    <span>2</span>
    <span>3</span>
    <span>4</span>
    <span>5</span>
    <span>6</span>
    <span>6</span>
    <span>6</span>
    <span>6</span>
</div>
</body>
</html>